A generic coupling connection is known for example from EP 0 775 865 B1, which relates to an arrangement for connecting a corrugated pipe to a coupling element. The coupling connection has a support ring which can be screwed into the corrugated pipe and the end of which protrudes from the corrugated pipe. An annular element configured as a pressure ring is screwed far enough onto the corrugated pipe that the end of the corrugated pipe protrudes out. Together with the pressure ring, the coupling element forms a sealing chamber, in which a graphite sealing ring is arranged. The sealing ring is deformed and compressed as a result of the pressure ring and connection element being pulled together axially. Bolts are provided for this purpose, or a separate tool if no bolts are used. In this variant, the compressed state is fixed in that the coupling element overhangs the pressure ring and the overhanging end is deformed. Alternatively, one or more pins as fixing elements may fix the pressure ring with respect to the coupling element.
EP 1 457 726 B1 likewise relates to attaching a coupling connection of this type to a helically corrugated metal pipe, in which a support ring is screwed far enough into the end of the metal pipe that a smooth-walled region having a smaller external diameter than the clear width of the metal pipe both remains within the metal pipe and overhangs the end of the metal pipe, in such a way that a coupling piece can be inserted between the metal pipe and the support ring. As a result, a graphite sealing ring, arranged on the circumference of the smooth-walled region of the support ring, is axially and radially deformed and compressed between the coupling piece and the pressure ring. For this purpose, holes in the flange in the pressure ring of the coupling piece make it possible to bring the flanges together using bolts.
The high complexity of manufacture, linked to the required low tolerance in the connection region of the support ring with respect to the coupling piece, is found to be a drawback of the above-described coupling connections. In particular, on the one hand, the relative movability has to be ensured, so as to be able to compress the sealing ring in the sealing chamber; on the other hand, the fluid supplied to the corrugated pipe should be reliably prevented from penetrating into the interior of the sealing chamber.
Of course, forming the support ring and the coupling piece in one piece has also been considered, but in the coupling connections this means dispensing with the sealing ring, which is in turn required for the pressure ring and the reliable transmission of the forces which occur during operation.
Another connection type for corrugated metal pipes is described in DE 33 02 450 C2. A support bushing is screwed onto the end of a corrugated pipe and a pipe connector is screwed into the end of the corrugated pipe. The sealing is brought about in that the clear width of the support bushing increases towards the end or the external diameter of the pipe connector decreases towards the end. When the pipe connector is screwed into the corrugated pipe end, which is adapted to the internal contour of the outer bushing using a forming tool, the corrugated pipe is sealed between the pipe connector and the support bushing.
DE 40 27 818 A1 discloses a coupling fitting for corrugated pipes, which comprises an outer bushing, screwed onto the corrugated pipe end and having a smooth pipe attachment overhanging the corrugated pipe end. The smooth pipe attachment has an internal thread, into which a coupling pipe piece is screwed. A stepped end of the coupling pipe piece penetrates into the corrugated pipe. When the coupling pipe piece is screwed in, the corrugation of the corrugated pipe is buckled. The sealing is provided by a graphite sealing cord, which is laid in the last corrugation waves and which deforms when the corrugation is buckled and is pressed against the inner wall of the outer bushing and the stepped end of the pipe connector penetrating into the corrugated pipe end.
DE 33 41 297 C2 discloses a sealing packing for sealing corrugated pipes, which is formed from two bushings, which are arranged movably with respect to one another on the corrugated pipe and fit inside one another, and between which an annular space surrounding the corrugated pipe is formed for receiving a graphite sealant. A corrugated pipe sleeve, applied to the sealing region from the inside, is provided.
It is further known from CH 589 249 A5 to roll the end of a corrugated metal pipe against the inner face of a flange, smoothing out the corrugation. As a result of the high contact pressure which occurs during the rolling, a tight press fit comes about between the previously corrugated metal pipe and the metal flange. This type of connection requires a high equipment outlay at the assembly site and necessitates thick-walled cast parts.